苜蓿干草对杜寒杂交羊瘤胃发酵参数及十二指肠食糜氨基酸含量的影响

Effects of Dried Alfalfa Hay on Ruminal Fermentation Parameters and Amino Acid Contents in Duodenal Chyme of Dorper×Thin-Tailed Han Crossbred Sheep

本试验旨在研究苜蓿干草对杜寒杂交羊瘤胃发酵参数及十二指肠食糜氨基酸含量的影响。选用5只安装永久性瘤胃和十二指肠瘘管的杜寒杂交羊(F1代),采用5×5拉丁方设计,设计5个水平的苜蓿干草,其在粗饲料中的比例(干物质基础)分别为0(对照组)、10%(试验Ⅰ组)、20%(试验Ⅱ组)、30%(试验Ⅲ组)和40%(试验Ⅳ组)。共5期试验,每期包括7 d预试期和10 d正试期。结果表明:1)粗饲料中苜蓿干草比例对瘤胃液pH和氨态氮的含量无显著影响(P>0.05)。2)各组瘤胃液尿素氮含量变化趋势基本一致,除了采食后5 h试验Ⅰ组显著高于其他各组(P<0.05)外,各时间点试验组之间及试验组和对照组之间差异均不显著(P>0.05)。3)随着粗饲料中苜蓿干草比例的增加,瘤胃内的发酵方式由丙酸型转化为乙酸型。4)试验Ⅰ、Ⅳ组十二指肠食糜中缬氨酸、蛋氨酸和亮氨酸含量显著高于对照组(P<0.05),试验组之间差异不显著(P>0.05);试验Ⅰ组的异亮氨酸含量显著高于试验Ⅲ组(P<0.05),与对照组及其他试验组差异不显著(P>0.05)。结果提示,苜蓿干草可以改善杜寒杂交羊的瘤胃发酵,提高氮利用效率及十二指肠中部分氨基酸含量;本试验条件下,粗饲料中适宜的苜蓿干草比例为10%。

The purpose of this experiment was to investigate the effects of dried alfalfa hay on ruminal fermentation parameters and amino acid contents in duodenal chyme of Dorper×thin-tailed Han crossbred sheep. Five Dorper×thin-tailed Han crossbred sheep （F1 generation） with ruminal and duodenal fistulas were used in a 5×5 Latin square design. Five levels of dried alfalfa hay were designed, and its percentage in roughage was 0 （control group）, 10% （test group Ⅰ）, 20% （test group Ⅱ）, 30% （test group Ⅲ） and 40% （test group Ⅳ）, respectively. There were five test periods, each of them consisted of a 7-day pre-test period and a 10-day test period. The results showed as follows： 1） the percentage of dried alfalfa hay in roughage had no significant effects on rumen fluid pH and ammonia nitrogen content （P〉0.05）. 2） The content of urinary nitrogen in rumen fluid of different groups showed a similar tendency, except that test group Ⅰ was significantly higher than the other groups （P0.05）. 3） With the increase of dried alfalfa hay percentage in roughage, the fermentation style in rumen was converted from propionic acid into acetic acid. 4） The contents of valine, methionine and leucine in duodenal chyme of test group Ⅰ and Ⅳ were significantly higher than those of control group （P0.05）; the isoleucine content of test group Ⅰ was significantly higher than that of test group Ⅲ （P0.05）. The above results indicate that dried alfalfa hay can improve ruminal fermentation, increase nitrogen utilization and the contents of some amino acids in duodenum; under conditions in the present study, the optimal percentage of dried alfalfa hay in roughage is 10%.